Developmental theorists have provided compelling arguments that subtypes of mental disorders commonly follow distinctive developmental trajectories reflected in the age of onset and subsequent course of symptoms over time. Over the past decade the Principal Investigator and colleagues have developed a specialized form of discrete mixture modeling to identify such distinctive groups of individual trajectories and to uncover the distinguishing characteristics of trajectory group members. The proposed research program will make the following advances in the methodology. Identification of factors that change developmental trajectories-The base model will be generalized to provide trajectory group-specific estimates of whether and to what degree a turning point event (e.g., marriage), an intervention (e.g., counseling), or an ecological factor (e.g., neighborhood poverty) alters the developmental course of a psychiatric disorder. Prediction-Dynamic prediction of an individual's developmental course of diagnosis, symptoms, and functioning is important for both scientific and clinical purposes. Predictive tools will be developed and demonstrated that provide the capability for prospectively predicting trajectory group membership and behavior. Important Technical Issues-The proposed research will address several fundamental technical issues that are important to proper application of the methodology, including the above extensions. Expanded Software Functionality, Dissemination, and Application- Key aspects of dissemination are continued development of "canned" SAS-based software for model estimation and application of the method to important substantive problems.